计算将 SQLite 连接到Python后所做更改的总数

在本文中，我们将了解如何计算自 SQLite 数据库连接使用Python打开以来的总变化。为了获得更改的总数，我们使用连接对象的total_changes属性。

Class Instance: sqlite3.Connection

Syntax: .total_changes

Return Value: Total no. of rows inserted, deleted, updated since the database connection is open.

出于演示目的，我们将使用存储在geeks.db数据库中的person表。

表定义：

CREATE TABLE person(
id INTEGER PRIMARY KEY AUTOINCREMENT,
name TEXT NOT NULL,
age INTEGER NOT NULL);

例子：

Python3

# Complete python program to get 
# the total no. of change since the
# beginning of the database connection.
  
# Import sqlite3 module to work with
# SQLite using python.
import sqlite3
  
# Create connection object by connecting
# to the required database (here geeks.db)
con = sqlite3.connect('c:/sqlite/db/geeks.db')
  
# SQL string to Create a database table
# named person.
create_table = '''CREATE TABLE person(
                  id INTEGER PRIMARY KEY AUTOINCREMENT,
                  name TEXT NOT NULL,
                  age INTEGER NOT NULL
                  );'''
  
# Execute the above SQL query.
con.execute(create_table)
  
# Print the current total no. of changes.
print("Total changes inititally:")
print(f'total_changes = {con.total_changes}\n')
  
# SQL string to insert records into 
# the table named person.
insert_data = '''INSERT INTO person(name, age)
                  VALUES ("Yogesh",21),
                  ("Vishal", 22),
                  ("Ajit",22),
                  ("Ashish",21),
                  ("Tanvi", 20);'''
  
# Execute the above SQL query.
con.execute(insert_data)
  
# Print the current total no. of changes.
print("Total changes after inserting 5 rows:")
print(f'total_changes = {con.total_changes}\n')
  
# SQL string to Select (retrieve) records
# from a database table named person.
select_data = 'SELECT * FROM  person;'
  
# Execute the above SQL query.
cursor = con.execute(select_data)
  
# Create a list of column names of the
# database table named person.
header = [d[0] for d in cursor.description]
  
# Print the column names separated 
# by a single space.
print(*header)
  
# Print the retrieved data.
for row in cursor:
  print(*row)
print()
  
# SQL string to delete a record from a
# database table named person.
delete_data = 'DELETE FROM person WHERE name="Tanvi";'
  
# Execute the above SQL query.
con.execute(delete_data)
  
# Print the current total no. of changes.
print("Total changes after deleting a row:")
print(f'\ntotal_changes = {con.total_changes}\n')
  
# Retrieve the modified (here deleted
# one record/row) data from a database
# table named person.
cursor = con.execute('SELECT * FROM person;')
  
# Print the retrieved data.
print(*header)
for row in cursor:
  print(*row)
print()
  
# Commit the changes to persist the
# changes.
con.commit()
  
# Close the database connection.
con.close()

输出：